Abstract: In this experiment, different concentrations of epigallocatechin gallate (EGCG) was induced to interact with soy protein isolate (SPI) to form complexes, aiming to explore the change of SPI structure and the effect of heat treatment on the composite system. The results showed that the mechanism of action of EGCG on SPI was static quenching by non-covalent hydrophobic interaction. Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy showed that binding to EGCG increased the percentage of α-helix and decreased the percentage of β-sheet structure in SPI before and after heat treatment, but resulted in no significant changes in the percentages of β-turn or random coil. The fluorescence and UV-visible spectra demonstrated that the interaction between EGCG and SPI caused a red shift in the maximum emission wavelength of SPI, and heat treatment enhanced this tendency.

Key words: soy protein isolate; epigallocatechin gallate; heat treatment; interaction mechanism; structure